A new method has been developed that permits the regular 1H spectrum of a molecule to be separated in a number of subspectra of limited fragments of the molecule. This simplifies spectral assignment and permits the exact measurement of coupling constants for spectral regions that were previously unaccessible. The method lengthens the apparent relaxation time of the nuclei during the mixing process which yields a large sensitivity enhancement in the study of macromolecules. New two-dimensional NMR methods utilizing protons for indirect detection of nuclei with a low magnetogyric ratio (e.g. 13C, 15N) have been developed. These methods offer an increase in sensitivity of more than an order of magnitude relative to other modern NMR techniques. The methods can be used for detecting either direct (one-bond) connectivity or long range (multiple-bond) connectivity. This latter application has been shown to be extremely useful for structure determination of unknown compounds. These new NMR techniques have been used to determine the structure of the antibiotic desertomycin and to reassign the spectrum of coenzyme B12. The solution structure of coenzyme B12 has been studied by using spin-locked NOE spectroscopy.